Intraluminal medical devices such as catheter assemblies are often inserted into a patient at a location remote from the treatment site. For instance, these devices are often inserted into the femoral artery in the groin area, and are then maneuvered through the femoral artery and into position in the upper cardiovascular region. The materials routinely used in the manufacture of such devices are often not inherently lubricious. In order to facilitate insertion and navigation through the body vessels and to therefore make this type of procedure less traumatic for the patient, lubricious coatings can be applied to the surfaces of the devices to reduce the friction between the device surface, and whatever other surface with which it comes into contact.
Lubricants come in both hydrophilic and hydrophobic varieties. Hydrogels are one class of hydrophilic lubricants. Hydrophobic lubricants include oils such as olive oil and sesame oil, glycerine, and silicone based compounds.
One commonly used silicone lubricant is polydimethylsiloxane. This lubricant is a clear, water white liquid that is typically applied to the surface of a medical device as a solution, or it may be applied neat. The lubricant is applied in very small amounts. The clarity and amount of coating applied, along with the very small size of these medical devices makes visual inspection of the amount and location of the coating very difficult, however. Adding color to the coating in the form of a dye or pigment is typically not a desirable option when used on medical devices.
A couple of different methods have been utilized to determine the presence and adequacy of a lubricious coating but they are considered as being “destructive” methods. The first is to carefully weigh pre-identified catheters, run them through the coating process, and then weigh them again to determine coat weight. This allows a gross determination of the amount of coating (such as a silicone coating) on a catheter, but is considered to be a destructive method because the identified catheter cannot be used. Furthermore, this does not allow visualization as to where the coating is located on the device, or the quality or uniformity of the coverage.
A second method involves removing the coating from the surface of the catheter with a solvent, evaporating the solvent, and weighing the coating. This method is more cumbersome, and it also does not indicate the quality or uniformity of the coverage.
U.S. Pat. No. 5,807,605 describes a non-destructive method for visualization of a polydimethylsiloxane coating on a surface of a medical device which includes dissolving a fluorescent agent into the polydimethylsiloxane lubricant and applying the fluorescenated polydimethylsiloxane lubricant to the surface of the medical device.